Imagine if you will a beautiful sunny day. You’re walking along, have your camera of course, and come upon a beautiful place to snap a shot. You get all ready to shoot and then it hits you! Uh oh, you left your light meter at home! This is terrible, how are you going to set the proper exposure for your sunny day photo? In fact not only did you realize you left your light meter at home, you remember that it’s really the light meter you’ve only been thinking about buying, you don’t even own a light meter yet!

Fear not, it turns out there is a way that you can set a close to perfect exposure on a nice bright sunny day without a light meter. This is excellent news for those of you who left your light meters at home, or haven’t gotten around to buying one yet (you know who you are out there). Enter…the Sunny 16 rule! It’s not just a record title by Ben Folds.

The Sunny 16 rule can be used as a guide to set a near perfect exposure when shooting on a sunny day. Here’s how it works. First switch to Manual Exposure mode on your camera. Not sure about Manual Exposure Mode? Just check a few blog posts back for our series on Exposure Modes. Next set your aperture to f/16 (that’s the 16 part of the Sunny 16 rule for those of you who were curious). Then set your shutter speed to the nearest full stop reciprocal of your ISO (what did he just say, did he just curse me out?).

Relax, reciprocal simply means to take the inverse of your ISO setting. So if your ISO is set to 100, then the reciprocal is 1/100. If your ISO is set at 200 then the reciprocal is 1/200. Hang on a minute though, I did say the “nearest full stop” to the reciprocal right? This is true, there are many cameras that only let you set your shutter speed to full stop settings, 1/100 and 1/200 are not full stop settings so you may not be able to use those on your camera. This is why we use the nearest full stop to the reciprocal. So if your ISO is set to 100, the reciprocal is 1/100 and we would use a shutter speed of 1/125. This is because 1/125 is the nearest full stop to 1/100. If our ISO is set to 200, the reciprocal is 1/200 and we would use a shutter speed of 1/250 because that is the nearest full stop to 1/200. Here is a list to refresh your memory about the full stop values with regard to shutter speed.

Shutter Full Stop Values: 1s, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000, 1/2000

So what is ISO? ISO is basically a setting of how sensitive the sensor in your digital camera is to light, or how sensitive your film is to light. The difference between the 2 is that with a digital camera you can change your ISO with the touch of a button, in a film camera you actually have to put a new role of film in. Most digital cameras set the ISO automatically for you, and use ISO 100 or ISO 200 most of the time, of course it is possible for you to change this setting, and then you would take the reciprocal of whatever you currently have your ISO set to. As a rule of thumb though on a bright sunny day you would typically use a low ISO of about 100 or 200, this is because there is plenty of light around you so your sensor or film doesn’t need any extra sensitivity.

That’s all there is to it! So the next time you find yourself shooting on a bright sunny day and don’t want to drag that light meter out of the camera bag you can use the Sunny 16 rule to make sure you have perfect exposure almost every time. It’s May, the weather is beautiful, go put the rule into practice and shoot some bright sun scenes. As always feel free to post the results or comment.

Here is a photo using the Sunny 16 rule, as you can see a very nicely exposed photograph, ignore the funny looking guy on the Segway, he thought he was in the 3 o’clock parade.

Properly Exposed Photo Using the Sunny 16 Rule, f/16, 1/250, ISO 200